Large Wind Turbines

Overview of Worldwide Wind Generation

This article is dated. For the most current statistics on wind development worldwide, contact BTM Consult and order a copy of their World Market Update.

Abstract

An overview of wind development activities in North America, Europe, and Asia, including a look at installed capacity, generation, specific yield, and environmental impacts.

Introduction

Wind energy is no longer the domain of a disheveled miller with corn flour in his hair, furling the cloth sails on his wooden windmill. Wind energy has come of age as a commercial generating technology. Whether it's for a nomadic herdsman on the Mongolian steppes, the women fetching water in a small village in Morocco, a farmer in Minnesota, a neighborhood cooperative in Denmark, or an operator of a wind power plant in one of California's windy mountain passes, wind energy offers proof that a sustainable energy supply is not just another pipe dream.

Not since the wind was used to sail the world's seas and pump water from the lowlands of Northern Europe has wind energy been used on such a grand scale as is now found in California, Europe, and Asia.

By any measure the power in the wind is no longer an alternative source of energy. The numbers are telling. Production of wind-generated electricity has risen from practically zero in the early 1980s to more than 20 Terawatt-hours (TWh) per year in 1999--a commodity worth nearly US$1 billion.

World Wind Capacity

Cumulative generating capacity worldwide topped 10000 Megawatts (MW) in 1998. Manufacturers installed more than 2400 MW of wind-generating capacity worldwide last year and expect to install another 2000 MW in 1999. Investment in wind generating capacity exceeded US$3 billion in 1998 for the first time. Germany and Denmark accounted for nearly one-half of new capacity. Germany now generates one percent of its electricity with wind power while Denmark produces ten percent of its supply with wind turbines. Germany Leads the Way

Germany's installed wind capacity has surpassed that of the entire North American continent. According to data compiled by the Deutches Windenergie Institut (DEWI) in Wilhelmshaven, total installed wind-generating capacity reached nearly 2900 MW in Germany at the end of 1998. There was nearly 800 MW of new capacity installed in Germany last year. For comparison, 400 MW were installed during the peak of California's wind development in 1985. The German market alone represents about US$1 billion dollar in wind turbine sales.

California's Decline Arrested

Installed wind capacity fell 110 MW from 1609 MW in 1994 to slightly less than 1500 MW in 1997. The installation of new wind turbines at formerly abandoned sites (Cabazon for example) increased operating capacity for the first time in several years. Total operating capcity at the end of 1998 was about 1550 MW. The number of operating wind turbines fell by about 2000 turbines from 14577 to 12700 in 1998.Revenues have fallen even more sharply. With the majority of the state's projects now receiving significantly less than $0.05/kWh, total sales of electricity have fallen from a probable high of $300 million per year to only $150 million per year or less.

However, repowering of aging California wind plants has arrested the decline in the states' wind capacity. The newer, more powerful turbines should also arrest the gradual decline in energy generation and help maintain production around the 3 TWh mark.

Historical Background

It is easy to forget the contribution wind energy has made to Western development. The 700 windmills in the Zaan district north of Amsterdam formed the nucleus of what would become the center of Dutch manufacturing in the 17th century and helped spur the industrial revolution. Wind energy was eclipsed by steam only at the end of the last century. As late as 1850, 90% of the power used in Dutch industry came from the wind. In the United States 77 firms were manufacturing farm windmills in one form or another in the late 19th century. Catalogues of the day bristled with choices.

Despite being overshadowed by fossil fuels, wind energy has never completely fallen out use. Today more than 1 million American farm windmills are still in use worldwide. These wind machines deliver more than 250 MW in pumping power to rural peoples around the globe.

Revival of interest in wind energy in the 1970s prompted dramatic advancements in the technology. Now modern airfoils and materials enable today's wind turbines to extract 10 times more power from the wind than the European windmill 100 years earlier.

Percent Penetration

Wind turbines in California produce about 1% of total in-state generation and have been doing so for almost a decade. While this may not seem like much, California has one-twelfth of the U.S. population and the world's seventh largest economy, and emits nearly as much carbon dioxide as the entire nation of France. In Germany, recently installed turbines supply 3% of the electricity consumed in Niedersachsen (Lower Saxony), one of the nation's most densely populated länder. In the nearby state of Schleswig-Holstein, wind energy meets 15% of electricity needs.

Wind turbines met 6% of the electrical needs of 5 million Danes in 1997 to 1998. Installations in 1998 has raised penetration in Denmark to the 10% mark. (Data in the following table is from 1997. Data from 1998 was not available when this article was posted.) When winds are strong and demand weak, wind turbines pump as much as 36% of the supply into electrical network of the Jutland peninsula.

In some areas of the world wind turbines are providing a suprisingly high percentage of the electricity. In the Danish township of SydThy in northwest Jutland, wind turbines generate 95% of the area's electricity. Further south in central Jutland, wind turbines produce some 40% of Ringkøbing Commune's electricity. On the small island of la Desirade off the coast of Guadeloupe, wind turbines generate 80% of the annual supply of electricity and with the addition of several more turbines will be able to export electricity to the mainland.

Developing World

Wind energy is not proprietary to the industrialized world. Developing countries, such as India and China, have industrial infrastructures sufficient to build wind turbines. Other Third World nations have demands for energy that wind turbines are ideally suited to provide.

Though small wind turbines, such as the 10,000 micro turbines China churns out each year, produce little electricity in absolute terms, these machines furnish important services. One kilowatt-hour of electricity provides 10 times more services in India than it does in the state of Indiana. Two 10-kilowatt wind turbines, which would supply only two homes with electric heat in the United States, can pump safe drinking water for 4000 people in Morocco. Two such wind turbines have liberated the women of Ain Tolba from walking several kilometers every day for water. Developing countries are increasingly turning to wind and solar energy as a cost-effective way to meet the electrical needs of rural areas without the environmentally damaging expansion of central-station power.

Cost-Effectiveness

Today's wind development boom results from wind energy's new found cost-effectiveness and a willingness on the part of certain nations to make renewable energy a priority. Wind technology has come of age as reliability and productivity have improved and costs have declined.

During the early 1980s wind turbines in California were available for generation, the industry's measure of reliability, only 60% of the time. After more than 15 years of slow but steady progress, it is now common for wind turbines to be available for operation 97-99% of the time. Today, anything less is unacceptable.

As reliability has improved, so has productivity. When measured in kilowatt-hours produced annually relative to the area swept by a wind turbine's rotor, productivity has progressively increased among turbines that were installed in the 1980s. But newer wind turbines are far more productive than earlier models. California, with one-third of the world's installed wind capacity, has seen its fleet average rise from 500 kWh/m2/yr in the early 1980s to 800 kWh/m2/yr in the mid 1990s. Today it is not uncommon for well designed, well maintained wind turbines at windy sites to generate 1000 kWh/m2/yr. Some machines at exceptionally windy sites produce as much as 1500 kWh/m2/yr.

Meanwhile, installed costs have fallen as dramatically as productivity has risen. The installed price for new medium-sized wind turbines has plunged from US$4,000 per kilowatt in 1980 to US$1,250 today. The resulting cost of energy has slid from more than US$0.40 per kilowatt-hour in the early 1980s to as low as US$0.06 per kilowatt-hour today under ideal conditions--a price well within striking distance of conventional fuels.

Despite these accomplishments, skeptics still find fault with the technology, suggesting that wind turbines are too land- and material-intensive for widespread use.

Energy and Land Intensity

Though wind turbines do use energy-intensive materials, such as steel, glass reinforced polyester (fiberglass), and concrete (for foundations), they quickly repay the energy consumed in their construction. At good sites, wind turbines pay for the energy in their materials within the first three to four months. Even at poor sites, energy payback occurs in less than one year.

The Achilles' heel of renewables, especially wind energy, has always been the charge that they are too land-intensive, even for such land rich continents as North America. Wind turbines do occupy more land than other energy technologies. The amount of land needed varies from as little as 5 hectares (12 acres) per MW for California's densely packed arrays to the 15 hectares (36 acres) per MW found in the openly spaced wind plants of northern Europe. As a rule, open arrays like those in northern Europe, where wind turbines are spaced 5 rotor diameters apart across the wind and 8 diameters apart downwind, occupy 50 square meters of land for every square meter swept by the wind turbine's rotor.

Fortunately, modern wind plants use no more land than that consumed in the fuel cycle of coal. In some European wind plants, farmers till the soil to the base of the towers. At others sheep graze the entire site, including the service roads. At European wind plants, as little as 1% of the land occupied by the wind turbines is used for the turbines, their foundations, service roads, and ancillary structures. Even if the wind turbines used 5% of the land occupied, a wind plant in a moderately strong wind regime will use less land than a coal mine and conventional power plant producing the same amount of electricity during a 20 year period. And wind turbines generate this electricity without the emissions associated with fossil fuels.

Emissions Offset

The direct generation of a unit of electricity, whether from wind or water, offsets the combustion of three units of fossil fuel in a conventional power plant. Every kilowatt-hour produced by a wind turbine offsets the emission of 0.5 to 1 kilograms (1-2 pounds) of carbon dioxide from conventional sources. Wind generation also offsets up to 7 grams (0.015 pounds) per kilowatt-hour of sulfur oxides, nitrogen oxides and particulates from the fuel cycle for coal, including mining and transport, 0.1 gram (0.468 pounds) per kilowatt-hour of trace metals, such as mercury, and more than 200 grams (0.5 pound) per kilowatt-hour of solid wastes from coal tailings and ash. The amount of pollutants offset depends upon the mix of fossil fuels, nuclear power, and hydro-electricity used in the existing fuel cycle. Wind generation offsets more air pollutants from utilities dependent on coal than those burning natural gas.

Wind generation now offsets some 10,000 million kilograms (20,000 million pounds) of global warming gases annually and, at the present growth rate, will offset nearly twice that by the year 2000. While only a modest contribution globally, wind energy is already making a difference in specific regions.

Impacts

While a relatively benign technology, wind energy is not free of environmental impacts. Wind turbines are audible to those nearby, and wind turbines in California's Altamont Pass and in southern Spain have killed some birds. Fortunately, wind energy's impact on birds is site specific. Noise can be reduced by the greater use of sound insolation and isolation within the nacelle, and the use of new quieter airfoils. Careful siting can reduce impacts on both people and birds.

Wind turbines are also visible for great distances on certain landscapes. Though the turbines may be visible, they are not necessarily intrusive, and careful consideration of a wind turbine's or a wind power plant's appearance can ameliorate aesthetic concerns.

Valuing Benefits

Thus, it is no longer a question of whether or not wind energy will be used, but where, and at what rate its role will grow. There are ample wind resources on most continents to make a sizable contribution toward a sustainable energy supply. There are sufficient wind resources in the United States, for example, to meet 27% of the nation's 1990 electricity consumption with current technology. The wind turbines needed to do so would occupy only 0.6% of the lower 48 states after excluding environmentally sensitive lands. There are even greater wind resources in Canada. But price and public policy will determine the rate at which these resources are developed.

Where nations value the air quality and other benefits wind energy provides, public policy follows by removing restrictions on the interconnection of wind turbines with the utility system, and by offering just compensation for wind-generated electricity. In a simple demonstration of the power of market forces, wind energy is growing fastest where the tariffs for wind-generated electricity are greatest.

No country illustrates this better than Germany. Though Germany has had an aggressive research and development program for nearly two decades, the rapid growth of wind energy began only after the German government established nationwide tariffs in late 1990 for the sale of wind-generated electricity. These generous tariffs attracted the keen interest of the private sector.

Germany's "electricity feed law," the stromeinspeisungsgesetz, requires utilities to buy wind generation at 90% of the retail price. This corresponded to 0.17 DM/kWh (US$0.10/kWh) in 1998. The German government also provides low-interest loans to projects, such as the installation of wind turbines, designed to protect the environment. Small farmers and cooperatives are encouraged to use the loans and borrowers may apply for up to 100% of a wind turbine's cost for ten years at an attractive rate of 6.5% interest.

Denmark, which agreed to reduce its carbon dioxide emissions by 10% before the year 2000, has taken a similar approach. Denmark's Folketing or parliament has established a nationwide buy-back tariff for wind energy, and has excluded wind generation from the nation's electricity and carbon taxes. Danish utilities buy wind-generated electricity from private wind turbine owners at 85% of the pre-tax retail rate. Coupled with exemptions from taxes on electricity and carbon dioxide, homeowners, farmers, and cooperatives generating their own electricity receive the equivalent of 0.561 DKK/kWh (US$0.093/kWh).

The steady growth in the private sector encouraged by these prices, alongside the growth in the Danish utility program, will enable Denmark to reach their year 2000 goal.

Wind energy continues to grow apace in countries such as Germany and Denmark where public policies place a high value on wind's environmental benefits. Wind energy remains stymied where issues of air quality and the sustainable use of indigenous resources are of lesser importance.

As we approach the millennium, it becomes increasingly clear that wind energy is no longer an alternative source of energy. Wind works. We only have to choose to use it.